Similarly, we observed no change in either Ki67 or p21CIP1 in bronchi/bronchioles compared to controls (Supplementary Fig. 9C, D), thus enforcing the evidence that the proliferation induction and p21CIP1 activation in non-tumor alveolar parenchyma and in bronchi/bronchioles observed in tamoxifen-treated BRAFV600E mice is an immediate and acute effect of BRAFV600E expression rather than a cumulative effect over time of random events of Cre-dependent recombination of BRAFV600E allele which may lastly result in a basal/chronic BRAFV600E-activation. The gene discussed is MKI67; the disease is neoplasm.